...So my question to the people here that have or do tattoos is--are just all tattoo artists just complete @sshats?
Two things to remember:
1. Tattoo artists are just like any other segment of society--some winners, and a whole lot of losers. I've met some who were decent people, and others who weren't. Also, in my experience, artists in general (regardless of the medium) are usually high-strung, and either overly confident or highly insecure with regards to their work. Either way, they don't respond to criticism well, and the stress of a competition like this tends to turn their @sshat meters up to 11.
2. Like all "reality" shows, you're seeing footage of a small portion of their week (approximately 45 minutes in this case). And the producers of shows like this like to focus on the dramas and conflicts that occur during that week because their audiences would rather watch a train wreck than watch rainbows and puppies.
Put those two factors together, and you realize you're not exactly seeing these people at their best.
As for the judges, they're not there to swap spit with the contestants in the shower in the wee hours of the morning; they're there to specifically point out the flaws in their work. The wise contestants listen to what they have to say, and make a serious attempt to improve on their weak points. But, as I stated above, some artists are overly confident and have a high opinion of themselves and their work that is completely unwarranted, and some of their work on this show proves that. Those are the contestants that don't listen to the judges, and keep making the same mistakes week after week. And, for the most part, I haven't seen the judges make any personal attacks unless a contestant starts mouthing off first; the one exception might be the aforementioned artist who had no tattoos.
With regards to other tattoo shows in which the artists seem to be "nicer", those artists don't have time deadlines or $100,000 on the line so they can afford to be more relaxed.